title: The effect of estrogen replacement therapy on plasma nitric oxide and endothelin-1 levels in postmenopausal women.
abstract: BACKGROUND
  Estrogen replacement therapy (ERT) in postmenopausal women decreases cardiac mortality and improves endothelial function. The endothelium regulates vascular tone and growth by releasing such factors as nitric oxide and endothelin-1.
  
  
  OBJECTIVE
  To determine whether ERT alters the balance between the total oxidized products of nitric oxide and endothelin-1.
  
  
  METHODS
  Single-arm, before-after clinical trial.
  
  
  METHODS
  Outpatient clinical research center of an academic medical center.
  
  
  METHODS
  15 postmenopausal women.
  
  
  METHODS
  Treatment with 17 beta-estradiol for 6 months and a 10-day course of methoxyprogesterone every 3 months.
  
  
  METHODS
  Plasma nitric oxide and endothelin-1 levels were measured at baseline and after 6 months of ERT.
  
  
  RESULTS
  The mean baseline nitric oxide level was 27.5 nmol/mL (range, 20.3 to 34.8 nmol/mL) and increased by a mean of 7.2 nmol/mL (range, 0.2 to 14.1 nmol/mL) (P = 0.04). The mean baseline plasma endothelin-1 level was 16.4 pg/mL (range, 12.0 to 20.8 pg/mL) and decreased by a mean of 3.9 pg/mL (range, 0.4 to 7.8 pg/mL) (P = 0.04). The mean baseline ratio of nitric oxide to endothelin-1 was 2.0 (range, 1.3 to 2.8) and increased by 1.2 (range, 0.1 to 2.2) (P = 0.03).
  
  
  CONCLUSIONS
  ERT results in an increased ratio of nitric oxide to endothelin-1. This may be one mechanism by which ERT provides cardiovascular benefit.
authors.affiliation: Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: P J
authors.initials: PJ
authors.lastname: Best
authors.forename: P B
authors.initials: PB
authors.lastname: Berger
authors.forename: V M
authors.initials: VM
authors.lastname: Miller
authors.forename: A
authors.initials: A
authors.lastname: Lerman
mesh_terms: D000368:Aged; D019332:Endothelin-1 / Q000097:blood*; D004958:Estradiol / Q000627:therapeutic use*; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008875:Middle Aged; D009569:Nitric Oxide / Q000097:blood*; D017698:Postmenopause / Q000097:blood*; D011374:Progesterone / Q000627:therapeutic use
chemical_list: D019332:Endothelin-1; D009569:Nitric Oxide; D011374:Progesterone; D004958:Estradiol